The present invention relates to the assembly of torque converter shells. More specifically the present invention relates to an improved method for attachment of vanes in impeller shells or turbine shells for an automatic transmission of a vehicle.
Torque converters for vehicles have varying vane configurations depending on the type of transmission and the level of performance desired. Typically, these vanes are initially assembled manually by hand or machine into a turbine shell or an impeller shell. The vanes must thereafter be secured therein by rolling the tabs down over a core ring to hold the vane in place prior to brazing functions or the like. Production of the torque converters using these steps has been labor intensive. It has therefore been a goal to reduce labor costs in the production of these parts.
Additionally, in the prior art, indexing tabs are used on the vanes for proper manual assembly of the vanes into the shells. Each of the indexing tabs requires a corresponding indentation or slot in each vane location on the shell, such that the vanes can be inserted in the shells for securement by brazing or the like. Thus, each different shell and vane configuration requires a specific machine for forming of the proper series of indentations in the shell. Because of this, several different machines are required to produce a diverse line of torque convertors. These machines are costly. Therefore, it is desirable to eliminate the need for these machines.
In the past after the vanes are installed in the shell by hand, a core ring is attached over the vanes and secured. The assembly is then brazed by placing a braze paste, braze powder or other braze material in close contact with the vanes and thereafter heating the assembly in an oven. Ideally the vanes are held in place in the shell such that there are very tight tolerances between the vanes and the shell. This allows the braze material to be drawn into the gap between the vane and the shell via capillary action for brazing of the vanes and securing them properly in the shell. However, occasionally during this process due to the differences in the properties of thermal expansion between the shell, which heats slowly, and the vanes, which are heated rapidly, there exists potential for warpage or other deformation of the assembly. During heating of the assembly, for brazing, the parts sometimes move with respect to one another. This causes out of spec conditions in the final part and often ruins the brazing step since larger than normal gaps may form between the vanes and the shell and/or vanes and the core ring. Thus, either the parts must be scrapped or further labor is required to repair certain portions of the completed shell prior to installation of the shells in the transmission.
Therefore, it has been a goal in the art to provide a new method for securement of vanes in turbine or impeller shells for torque converters such that lossage during production is reduced and costs associated with labor and machinery may be reduced during production of such torque converters.